Air pump



July 9, 1929. P. wlLLMANN AIR PUMP Filed Feb. 9, 1926 2 Sheets-Sheet I Iw W///////I///// I fr: 2% L Patented y 9,1929. UNITED STATES PAULWILLMANN, OF BERLIN, GERMANY.

1 AIR PUMP.

Application filed February 9, 1926, Serial My invention relates toimprovements in pumps for liquid gages, and more particularly in gagesof the type comprising an air pump adapted to deliver air under pressure6 into the tank containing the liquid at a point near the bottomthereof, and means for measuring the pressure of the said air, whichpressure depends on the height of the column of liquid within the tank.One of the objects of the improvements is to provide a system of thistype in which the valve of the air pump is controlled from the plungerof the pump through the intermediary of mechanical means, so that thevalve is automatically closed immediately at the begin- 'ning of thecompression stroke and automatically opened immediately at the end ofthe compression stroke. Another object of the improvements is to providea pump in which the plunger is automatically moved for performing thecompression stroke and retracted by hand for performing the suctionstroke. Other objects of the improvements will appear from the followingdescription.

For the purpose of explaining the invention several examples embodyingthe same have been shown in the accompanying drawings, in which the samereference characters have been used in all the views to indicatecorresponding parts. In said drawings,

Fig. 1, is an elevation partly in section showing my improved system,

Fig. 2, is a sectional elevation showing the air pump,

Fig. 3, is a elevation showing a modification of the system, and

Figs. 4 and 5, are sectional elevations showing modifications of the airpump.

' In the example shown in Fig. 1 my inproved system consists of a tank 7containing the liquid, an air pump 1 adapted to deliver air underpressure through a pipe 6 and into the tank 7 to a point near the bottomthereof, and means for measuring the pressure of the air delivered fromthe pump, said means being in the form of a manometer 5. When deliveringair from the pump 1 through the pipe 6 the pressure of the said airdepends on the height of the column of liquid above the delivery end ofthe pipe 6.

Therefore the said pressure can be used for determining the level of theliquid within the tank.

In the example shown in Fig. 2 the air pump consists of a cylinder 1provided at its bottom with a tubular member 8 having a No. 87,137, andin Germany April 1, 1925.

small bore and carrying two nipples 2 and 3, the nipple 2 beingconnected with the manometer by a pipe 4, and the nipple 3 beingconnected with the pipe 6. lVithin the pump there is a piston or plunger40 connected with a rod 41. At the bottom end of the cylinder there is avalve 9 acted upon by a spring 12 tending to close the valve. At itsinner end the stem 42 of the said valve carries a disk 11. The rod 41 isprovided at its bottom end with a projection 10 adapted to engage thedisk 11 for opening the valve 9 against the action of the spring 12. Thedisk 11 is adapted to belocked when the valve 9 is in depressed, openposition by means of a pawl 14 carried by a lever 13 which is rockinglymounted at the end 43 and is acted upon by a spring 44 which tends tohold the pawl 14 in looking position. .The lever 18 is connected by a.chain 15 with the plunger or piston 40.

Preferably the cylinder 1 of the pump is provided near its bottom with aportion of enlarged inner diameter 19 for the purpose hereinafterstated.

In the operation of the system the projection 10 of the rod 41 engagesthe disk 11 when the plunger 40 is near the lower limit of its strokeand hence depresses said disc and the valve 9 so that the latter isopened. The disc is locked in such depressed position by the pawl 14which is moved by the disc against the action of the spring 44, as willbe understood. When the plunger 40 moves upwardly the valve 9 is held inopen position by said pawl and disc so that fresh air is admitted to thecylinder 1. At the end of the upward or suction stroke of the plunger 40the lever 13 is pulled upwardly by the chain 15 so as to cause the pawl14 to release the disk 11 under the action of the spring 44, whereuponthe valve 9 is moved to closed position by the spring 12. The valve isclosed before the plunger is forced downwardly for delivering air intothe tank 7. During the downward or compression stroke the air deliveredthrough the nipple 3 has to overcome the pressure of the column of theliquid confined within the tank 7. The manometer 5 indicates the saidpressure and therefore the level of the liquid within the tank. Near theend of the compression stroke the plunger 40 gets into the portion 19 ofenlarged diameter sothat its frictional resistance is suddenly reduced,and the valve 9 is forced downwardly by the projection p 40 is forceddownwardly by hand.

10, the valve 9 being'lockcd in open position by the pawl 14. Now theplunger 40 is again moved upwardly in the manner described above. p

In constructions now in use the plunger I prefer to provide automaticmeans for this purpose,

and as shown a spring 16is provided within the upper part of thecylinder 1, which spring serves to force the plungerdownwardly.Preferably the handle 17 is not fixed to the rod-41, but is axiallyshiftable thereon, sothat it may be used only for pulling the plungerup\\*ardly, the rod 41 being provided at its top end with a collar 18which formsa stop for the handle. Therefore no downward pressure can beexerted byhand on the hand piece 17 and hence the plunger 40 is forceddownwardly solely by the spring 16; v

The modification shown in Fig; 3 is similar to the one described withreference to Figs: 1' and2, and the same reference char acters have beenused-to indicate correspondingp'a'rts. But the pipe 6 is not direct'lconnected} with the nipple 3, but throng the intermediary of'areceptacle20 the capacity of which is equal to the capacity of the cylinder 1. Ifby accident the valve 9 should not be opened at the'beginning of-thesuction stroke, the liquid taken upwardly through'thepipe '6 by thevacuum'within the cylinder 1 fills the receptacle 20 and does not entercylinder 1.

In Fig. 41" have shown a modification of the air pump l in which thevalve 45 is closed by the plunger 01' piston 46. As shown the valve 45'is acted upon by a spring 47 tending to open the. same, and it carries astem 22- loosely disposed within an" axial bore 48of the rod 21 of theplunger or-piston 46-- The said stem 22 is formed with a portion 24 ofreduced cross-section, and to the plunger 46 two clamping springs23'ar'e secured, which are adapted for clamping engagement with the mainportion of the stem 22; Inthe position of the plunger 46 shown in Fig; 4the clamping spri11gs-23 are" adjacent to the portion24 of reduceddiameter, and are out of frictional engagement with the rod 22. Thespring 4? opens the valve 45. When moving the 'plunger 46 upwardly bymeans ofith'eliandle 1"? for performing the suction stroke of the pumpthe clamping springs 23 engage the st'em22'thus holding the valve 45awayfrom its seat. At" the beginning of the downward or' compressionstrokeof the plunger the stem 22 is forced downwardly by" its frictionalengagement with the springs 23, so that the valve 45 is closed, untilthe springs 23 get into the position shown in Fig. 4,-in which thespring 47 opens thev alve. I

Fig. 4 shows separate nipples 49 for delivering the compressed airto thepipe 6 and the manometer 5.

In Fig. 5 I have shown a modification of the pump in whichthe valve ispositively connected with the plunger for being opened and: closedthereby. As shown the valve cone 50 carries a stem 26 jointed to a lever28 rockingly mounted at 27 and connected with a rod 29. The upper end ofthe said rod is bent inwardly as is shown at 30, and passes through aslot 31 of the wall ofthc cylinder 1 and the extreme end of said rod 29engages slidably in a slot 32 0f the piston rod 51.

In the position of the partssliownin Fig. 5, the valve 50 is open. Ifnew the'plu'nger 52 is moved upwardly for performingthe suctionstrokethe walls of the slot 32 slide along the end 30 of therod 29without engaging the same, and at the end of the upward movement of theplunger 'theshoulder 33 which forms the lower endofsaid slot 32 engagesthe end 30. Thereby'the lever 28is rocked upwardlyat' its left hand endand downwardly at its right hand end, thus closing the valve 29; If nowthe plunger 52 is moved downwardly for performing'the compression strokethe slot 32 doesnot'a'ct on the rods 29, 30, until the shoulder 34 atthe upper end of the'slot'engages'the'arrh 30 and movesthe left handend'of the lever 28 downwardly and its right hand end up wardly, thusopening the said valve For locking the valve in either positionthe'lever28 is formed at its'right hand end with'a' concave portion 35'engaged bya" latch bolt 36 adapted to be pressed into the concave portion by aspring 37. Thus the bolt locks the valve cone 50 in the position shownin Fig. 5. When forcing the valve cone 5O downwardly and'onit's-seat thebolt 36 rides on the concave portion 35 and engages an inclined face 53of the lever 28 thusholding the valve cone on its seat.

In Fig. 5 a partition wall 38is provided at the lower-end of thecylinderl and above the intalie valve 50 and'the outlet passages 54, andin a recess of the said partition wall there is a plate 55. The saidplate and the partition wall 38 are provided with small bores 39 adaptedto throttle the air forced by the plunger 52 through the outlet passages-54 to the manometer 5' and the pipe 6. By the said bores 39'theflow of the. air from thecylinder 1 to the manometer '5 and the pipe 6is throttled in case the pressure within the cylinder 1 is too high.Hence the pressure transmitted'to the pipe 6 and the manometer 5 doesnot exceedthe normal, even if an excessive pressure is exerted on theplunger.

While in describing the inventionreference has'been made to particularexamples embodying the same I wish it to be understood'that myinvention'is not limited to the constructions shown in the drawings, and

that various changes may be made in the general arrangement of theapparatus and the construction of its parts Without departing from theinvention.

I claim:

1. A hand operated air pump comprising in combination, a cylinder, apiston therein having a rod provided with a handle, a spring active toimpart a stroke to the piston in one direction, a valve controlling aninlet port in one end of the cylinder, a spring tending to close saidvalve, a latch device to hold said valve open, a connection between thelatch device and the piston to release the valve by movement of thepiston against the tension of the first named spring, means on thepiston to reengage said valve and latch device and a fluid outlet in thedischarge end of the cylinder.

2. A hand operated air pump comprising in combination, a cylinder, apiston therein having a rod provided with a handle, a spring to impartstroke to the piston in one direction, a valve controlling an inlet portof the cylinder, means cooperative with the piston to operate the valveat the end of a stroke of the piston and a fluid outlet in the dischargeend of the cylinder.

3. A hand operated air pump comprising in combination, a cylinder, apiston therein having a rod provided with a handle, a spring active tomove the piston in one direction, a valve controlling an inlet port ofthe cylinder, a spring active to move said valve in one direction, meansconnecting the valve to the piston for movement by the latter during apart of the movement of the piston and for release of the valve duringthe remainder of such movement of the piston.

In testimony whereof I hereunto affix my signature.

PAUL WILLMANN.

